In fact, levels of TRAP1 were reduced in human hepatocellular carcinoma cell lines depleted of S-nitrosoglutathione reductase (GSNOR), representing the best documented denitrosylase involved in regulating the levels of SNO-proteins in the cell (see section Enzymatic Regulation of S-nitrosylation). This evidence concerns the gene ADH5 and hepatocellular carcinoma.